Accuracy for STFTCNN does not improve after each epoch

After running the example notebook (CNN_STFT_model.ipynb) my accuracy does not increase even after 100 epoch, accuracy is stuck at 49% (subject 1). This is quite different from what is reported in sensors journal entitled : **Validating deep neural networks for online decoding of motor imagery movements from eeg signals**  could you rerun the notebook and share your result?